System and method for controlling LAN data flow control through a frame relay network by end point station transmitting notification to LAN stations based on congestion notification from the frame relay network

Abstract

The system and method of the present invention provide a mechanism, for the purpose of efficiently interconnecting local area networks (LANs) across a frame relay network, by which LAN stations provide data flow control when the frame relay network becomes congested. The system of the invention comprises a Station Manager at the network end point internetworking unit (IWU) for managing the IWU, a LAN Manager for managing one or more LANs connected to the end point IWU, and Station Managers at each of the LAN stations managing the respective LAN station. In operation, the IWU receives from the frame relay network a congestion notification and the IWU Station Manager broadcasts this notification to its managed LAN station Station Managers. The LAN station Station Managers each examine the notification against its outstanding data to be transmitted and slows down data traffic that is destined for the congested portion of the frame relay network.

What is claimed is: 
     
       1. For use with a frame relay network having an end point internetworking unit (IWU) connected thereto and one or more local area networks (LANs), each of said LANs conforming to one of a set of LAN protocols, all of said LAN protocols being different from the frame relay protocol, each LAN having one or more LAN stations connected thereto, said LANs being connected to said end point IWU so that said LAN stations may transmit data to said end point IWU for transmission over said frame relay network, said frame relay network providing a flow control mechanism for controlling the flow of data from said end point IWUs through said frame relay network, said frame relay network flow control mechanism comprising means for sending a frame relay network congestion notification identifying a congested portion of the frame relay network to said end point IWUs sending data to said congested portion, a system for controlling the flow of data from said LAN stations to said end point IWU, said system comprising: a frame relay protocol element, connected to said end point IWU, for receiving from said frame relay network a frame relay network congestion notification that said frame relay network is congested and for processing said frame relay network congestion notification to determine which portion of said frame relay network is congested;   an end point IWU station manager connected to said frame relay protocol element for transmitting a LAN notification identifying said congested portion in a format conforming to the LAN protocol, based upon said frame relay network congestion notification, to said LAN stations for said LAN stations to slow the flow of data to said end point IWU destined for said congested portion;   means, connected to said end point IWU station manager and said LAN stations, for receiving said LAN notification and   a plurality of LAN station managers, each LAN station manager being connected to a corresponding LAN station, for receiving said LAN notification, for processing said LAN notification identifying said congested portion of said network, for determining whether any data is to be sent from said LAN station to said congested portion of said network and, if so, for slowing the flow of data destined for said congested portion to said end point IWU from said LAN stations.   
     
     
       2. The system defined in claim 1 wherein said end point IWU comprises a router for transmitting data to said frame relay network from said LAN stations and to said LAN stations from said frame relay network. 
     
     
       3. The system defined in claim 1 wherein said end point IWU comprises a media access control (MAC) protocol element for acting as an interface between said frame relay protocol element and said end point IWU station manager. 
     
     
       4. The system defined in claim 3 wherein each of said LAN stations comprises a MAC protocol element and a logical link connection (LLC) protocol element, said LLC protocol element conforming to the IEEE 802.2 recommendation as having a dynamic window flow control mechanism. 
     
     
       5. The system defined in claim 4 wherein said end point IWU frame relay protocol element has a backward explicit congestion notification (BECN) mechanism. 
     
     
       6. For use with a frame relay network having an end point internetworking unit (IWU) connected thereto and one or more local area networks (LANs), each of said LANs conforming to one of a set of LAN protocols, all of said LAN protocols being different from the frame relay protocol, each LAN having one or more LAN stations connected thereto, each LAN station having a LAN station manager connected thereto, said LANs being connected to said end point IWU so that said LAN stations may transmit data to said end point IWU for transmission over said frame relay network, said frame relay network providing a flow control mechanism for controlling the flow of data from said end point IWUs through said frame relay network, said frame relay network flow control mechanism comprising means for sending a frame relay network congestion notification identifying a congested portion of the frame relay network to said end point IWUs sending data to said congested portion, a method for controlling the flow of data from said LAN stations to said end point IWU, said method comprising the steps of: in said end point IWU, receiving from said frame relay network a frame relay network congestion notification that said frame relay network is congested;   in said end point IWU, processing said frame relay network congestion notification and determining said congested portion;   transmitting a LAN notification identifying said congested portion, based upon said frame relay network congestion notification, said LAN notification being in a different format than said frame relay network congestion notification and conforming to the LAN protocol, from said end point IWU to said LAN stations for said LAN stations to slow down the transmission of data to said end point IWU destined for said congested portion;   receiving in said LAN station managers said LAN notification;   in each LAN station manager, processing said LAN notification identifying said congested portion of said network, determining whether any data is to be sent from said LAN station to said congested portion of said network and, if so, slowing the flow of data destined for said congested portion to said end point IWU from said LAN stations.   
     
     
       7. The method defined in claim 6 wherein said step of determining which portion of said frame relay network is congested further comprises the step of interpreting a data link connection identifier (DLCI) received from said frame relay network identifying said congested portion, and the step of converting said DLCI into a media access control (MAC) address associated with said congested DLCI. 
     
     
       8. The method defined in claim 7 wherein said step of slowing the flow of data destined for the congested portion of the frame relay network comprises the step of examining said MAC address associated with said congested DLCI against MAC addresses of data yet to be transmitted to determine whether there is a match and, if there is a match, slowing the flow of said data having MAC addresses which match said congested DLCI. 
     
     
       9. The method defined in claim 6 wherein said step of determining which portion of said frame relay network is congested further comprises the step of interpreting a data link connection identifier (DLCI) received from said frame relay network identifying said congested portion, and the step of converting said DLCI into a segment number. 
     
     
       10. The method defined in claim 9 wherein said step of slowing the flow of data destined for the congested portion of the frame relay network comprises the step of examining said segment number associated with said congested DLCI against segment numbers of data yet to be transmitted to determine whether there is a match and, if there is a match, slowing the flow of said data having segment numbers which match said congested DLCI. 
     
     
       11. For use with a frame relay network and one or more local area networks (LANs), each of said LANs conforming to one of a set of LAN protocols, all of said LAN protocols being different from the frame relay protocol, each LAN having one or more LAN stations connected thereto, said LAN stations having data for transmission across said frame relay network, said frame relay network providing a flow control mechanism for controlling the flow of data from said end point IWUs through said frame relay network, said frame relay network flow control mechanism comprising means for sending a frame relay network congestion notification identifying a congested portion of the frame relay network to said end point IWUs sending data to said congested portion, an end point internetworking unit (IWU) connected to said frame relay network and to said LANs for controlling the flow of data from said LAN stations to said end point IWU and across said frame relay network, said end point IWU comprising: means for receiving data from said LAN stations;   means for forwarding said LAN station received data across said frame relay network;   a frame relay protocol element for receiving data from said frame relay network;   means for forwarding said frame relay network received data to said LAN stations;   means for receiving from said frame relay network a frame relay network congestion notification that said frame relay network is congested and for processing said frame relay network congestion notification to determine which portion of said frame relay network is congested; and   an end point IWU station manager connected to said frame relay protocol element for transmitting a LAN notification identifying said congested portion in a format conforming to the LAN protocol, based upon said frame relay network congestion notification, to said LAN stations for said LAN stations to slow the flow of data to said end point IWU destined for said congested portion.   
     
     
       12. The end point IWU defined in claim 11 wherein said end point IWU comprises a router for transmitting data to said frame relay network from said LAN stations and to said LAN stations from said frame relay network. 
     
     
       13. The end point IWU defined in claim 11 wherein said end point IWU further comprises a media access control (MAC) protocol element for acting as an interface between said frame relay protocol element and said end point IWU station manager. 
     
     
       14. For use with a frame relay network having an end point internetworking unit (IWU) connected thereto and one or more local area networks (LANs), each of said LANs conforming to one of a set of LAN protocols, all of said LAN protocols being different from the frame relay protocol, each LAN having one or more LAN stations connected thereto, said LANs being connected to said end point IWU so that said LAN stations may transmit data to said end point IWU for transmission over said frame relay network, said frame relay network providing a flow control mechanism for controlling the flow of data from said end point IWUs through said frame relay network, said frame relay network flow control mechanism comprising means for sending a frame relay network congestion notification identifying a congested portion of the frame relay network to said end point IWUs sending data to said congested portion, a method for controlling the flow of data from said LAN stations to said end point IWU, said method in said end point IWU comprising the steps of: receiving from said frame relay network a frame relay network congestion notification that said frame relay network is congested;   in said end point IWU, processing said frame relay network congestion notification and determining said congested portion;   transmitting a LAN notification identifying said congested portion in a format conforming to the LAN protocol, based upon said frame relay network congestion notification, to said LAN stations for said LAN stations to slow the flow of data to said end point IWU destined for said congested portion.   
     
     
       15. The method defined in claim 14 wherein said step of determining which portion of said frame relay network is congested further comprises the step of interpreting a data link connection identifier (DLCI) received from said frame relay network identifying said congested portion, and the step of converting said DLCI into a media access control (MAC) address associated with said congested DLCI. 
     
     
       16. The method defined in claim 14 wherein said step of determining which portion of said frame relay network is congested further comprises the step of interpreting a data link connection identifier (DLCI) received from said frame relay network identifying said congested portion, and the step of converting said DLCI into a segment number. 
     
     
       17. For use with a frame relay network having an end point internetworking unit (IWU) connected thereto and one or more local area networks (LANs), each LAN having one or more LAN stations connected thereto, each of said LANs conforming to one of a set of LAN protocols, all of said LAN protocols being different from the frame relay protocol, said LANs being connected to said end point IWU so that said LAN stations may transmit data to said end point IWU for transmission over said frame relay network, said frame relay network providing a flow control mechanism for controlling the flow of data from said end point IWUs through said frame relay network, said frame relay network flow control mechanism comprising means for sending a frame relay network congestion notification identifying a congested portion of the frame relay network to said end point IWUs sending data to said congested portion, a method for controlling the flow of data from said LAN stations to said end point IWU, said method in at least one of said LAN stations comprising the steps of: receiving from said end point IWU a LAN notification based upon a frame relay network congestion notification, that said frame relay network is congested, said LAN notification conforming to the LAN protocol and in a different format than said frame relay network congestion notification;   processing said LAN notification and identifying from said LAN notification said congested portion of said frame relay network;   determining whether any data is to be sent from said LAN station to said congested portion of said network and, if so, slowing the flow of data destined for said congested portion to said end point IWU from said LAN station.   
     
     
       18. The method defined in claim 17 wherein said step of slowing the flow of data destined for the congested portion of the frame relay network comprises the step of examining said indication as to said congested portion against the destination of data yet to be transmitted to determine whether there is a match and, if there is a match, slowing the flow of said data having a destination which matches said congested portion.